bug#75164: treesit-font-lock-fontify-region is easy to lost color on parse error. suggest to remain fontify on parse error.

[Eval Exec <execvy@gmail.com>]

Hello.
When I enable rust-ts-mode on a rust file, I found treesitter is easy
to make emacs buffer to lost color.
For example, on the following rust code:
```rust

struct Dog {
    name: String,
    age: u8,
}


struct ManyStruct {
    a: u8,
}

fn many_code(){
    fn fib(n: u32) -> u32 {
        if n == 0 {
            return 0;
        }
        if n == 1 {
            return 1;
        }
        fib(n - 1) + fib(n - 2)
    }
}

fn main() {
    // change below `//` to `/` to see the difference
    // {
}
```

the rust code is right, and the emacs buffer color is right on every
struct/functions.
But, if I change `// {` to `/ {`, then the rust code is wrong, this
buffer will lost all colors.
You can see the change on bellow images:

https://imgur.com/a/4Tnv0GJ

I suggest emacs can remain colors even if the code is wrong.

My emacs version info: GNU Emacs 31.0.50